Downhole cutting tool and method of making

ABSTRACT

A downhole cutting tool includes, a body, a first contoured cutting element in operable communication with the body, and at least one contingency contoured cutting element in operable communication with the first contoured cutting element and the body. A contour of the at least one contingency contoured cutting element substantially matches a contour of the first contoured cutting element, and the at least one contingency contoured cutting element is maintainable in reserve and positioned to substitute for the first contoured cutting element if the first contoured cutting element becomes detached.

BACKGROUND

Downhole cutting tools commonly employ carbide cutters made of a solid piece of carbide. Although such cutters are effective at cutting the downhole materials they are designed to cut, their cutting efficiency, and effective lifespan, can be significantly reduced due to fracturing or chipping of the cutter. Fracturing and chipping can remove all or a portion of a cutting edge of the carbide cutter resulting in a dull and inefficient cutting tool. Well operators will therefore be receptive to tools and methods to increase the longevity of downhole cutters.

BRIEF DESCRIPTION

Disclosed herein is a downhole cutting tool. The tool includes, a body, a first contoured cutting element in operable communication with the body, and at least one contingency contoured cutting element in operable communication with the first contoured cutting element and the body. And a contour of the at least one contingency contoured cutting element substantially matching a contour of the first contoured cutting element, the at least one contingency contoured cutting element being maintainable in reserve and positioned to substitute for the first contoured cutting element if the first contoured cutting element becomes detached.

Further disclosed herein is a method of making a downhole cutter. The method includes, substantially matching a contoured cutting edge of at least one contingency contoured cutting element with a contoured cutting edge of a first contoured cutting element, and attaching the at least one contingency contoured cutting element adjacent the first contoured cutting element such that the at least one contingency contoured cutting element substitutes for the first contoured cutting element if the first contoured cutting element becomes detached.

Further disclosed herein is a downhole cutter. The cutter includes, a plurality of cutting elements having substantially matched contoured cutting edges, and a bonding material having greater ductility than the plurality of cutting elements bonding the plurality of cutting elements to one another in an arrangement such that detachment of one of the plurality of cutting elements reveals another of the substantially matched contoured cutting edges that substitutes for a contoured cutting edge of the detached cutting element.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 depicts a perspective view of a downhole cutting tool disclosed herein;

FIG. 2 depicts an enlarged perspective view of a portion of the downhole cutting tool of FIG. 1; and

FIG. 3 depicts an enlarged perspective view of a plurality of carbide cutting elements shown in FIG. 2.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring to FIG. 1, an embodiment of a downhole cutting tool 10 having a plurality of cutters 12 disclosed herein is illustrated. The tool 10 is just one embodiment of the invention to facilitate illustration of a break away construction of the cutter 12 that leaves a new cutting edge as will be disclosed in detail hereunder. In addition to the cutters 12, the cutting tool 10 includes, a tubular 14 and a plurality of articulatable bodies 18, also commonly referred to as arms or shanks. Each of the cutters 12 includes a plurality of contoured cutting elements 22A-22D attached thereto. The cutting tool 10 is positionable in a downhole wellbore via a drill string (not shown), for example, where it can be used to cut metal, earth or other materials whose removal is desired. The tool 10 can also be used to cut windows in walls of a wellbore, for example, to create a lateral wellbore from a primary wellbore. The plurality of contoured cutting elements 22A-22D are configured on the cutter 12 to break away from the cutter 12 in full elements 22A-22D, thereby limiting the extend of a fracture to a single element 22A-22D. In so doing, each time an element 22A-22C breaks free from the tool 10, a new (contingent) element 22B-22D becomes exposed with a new cutting edge that substitutes for the cutting edge of the detached element 22A-22C.

In this particular embodiment, the bodies 18 can articulate from a position wherein the cutters 12 are positioned radially inwardly of a diameter 26 that defines the tubular 14, to a position wherein the cutters 12 (during rotation of the cutting tool 10) trace out a diameter 30 that is substantially larger than the diameter 26. It should be noted that alternate embodiments of the cutting tool 10 could have fixed bodies 18 as well. A characteristic of any embodiment of the cutting tool 10 is that the tool 10 can move in such a way as to force the cutter 12 and cutting elements 22A-22D, attached to the body 18, to contact and thereby cut into a material intended to be removed.

Referring to FIGS. 2 and 3, the body 18, cutter 12 and contoured cutting elements 22A-22D are shown at greater magnification. This embodiment includes three stacks 34 of the contoured cutting elements 22A-22D that are attached at a distal end 38 of the body 18. Alternate embodiments could have a single stack 34 or more than three stacks 34. A first contoured element 22A in one of the stacks 34 has an exposed edge 46A that defines a first cutting contour 50A. The additional elements 22B, 22C and 22D, in any particular stack 34, have cutting contours 50B-50D that substantially match the first cutting contour 50A. The first cutting contour 50A can be formed to any desired shape practical by such methods as wire EDM, cutting with a diamond saw or by sintering, for example. Each of the elements 22A-22D are brazed, bonded, glued or welded to one another or to the body 18 with a bonding material 54.

Regardless of the bonding method used, the elements 22A-22D disclosed herein are made of a hard metal material such as tungsten carbide, titanium carbide or tantalum carbide, for example, or other hard material such as a ceramic (cubic boron nitride) or diamond. In embodiments disclosed herein the elements 22A-22D are made of tungsten carbide, also referred to as carbide. Carbide has exceptional hardness, a high melting point, and excellent wear characteristics when used as a cutting tool for cutting metal and earth formation materials. The elements 22A-22D, by design, are harder and more brittle than the bonding materials 54 employed and than the material of the body 18, which is made of a strong rigid material such as steel, for example. With the foregoing construction the more ductile bonding materials 54 and the body 18 will absorb much of the shock incurred while cutting. Should a load incurred be so great as to cause detachment of a portion of the cutter 12 the bonding material 54 should fail prior to fracture of one of the elements 22A-22D, thereby limiting the loss of a piece of the cutter 12 to that of an individual element 22A-22D. The foregoing construction thereby limits the loss of carbide volume from the cutter 12 due to each excessive load in comparison to a single solid piece cutter 12, for example. Additionally, should a fracture of an element 22A-22D occur the ductile bonding material 54 would prevent the fracture from propagating to an adjacent element 22A-22D, again limiting the size of a fracture chip to the size of an individual element 22A-22D.

Further, when, for example, the first element 22A of a stack 34 is detached at a bonding interface the contingent element 22B becomes exposed. And since the contingent element 22B has a contour 50B that substantially matches the contour 50A of the first element 22A, the contingent element 22B is positioned to substitute for and continue cutting of the target material. This substitution effect is possible because the first element 22A is displaced from the contingent element 22B in a direction according to arrow 58 (FIG. 1), defined by motion of the cutter 12 while cutting. Also, since the contour 50B of the contingent element 22B matches that of the first element 22A the desired original cutting profile can be maintained. A newly exposed contoured cutting edge 46B on element 22B having been formed in a similar fashion as the first contoured cutting edge 46A will be just as well suited for cutting and will be more durable and less susceptible to fracture than an edge randomly formed from a chip broken from a cutter 12 made of a single solid piece of carbide, for example.

Since each of the stacks 34 can have multiple contingent elements 22B-22D, with three contingent elements 22B-22D being illustrated in this embodiment, a new cutting edge 46B-46D can be reestablished several times without having to retrieve the tool 10.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. 

1. A downhole cutting tool comprising: a body; a first contoured cutting element in operable communication with the body; and at least one contingency contoured cutting element in operable communication with the first contoured cutting element and the body, a contour of the at least one contingency contoured cutting element substantially matching a contour of the first contoured cutting element, the at least one contingency contoured cutting element being maintainable in reserve and positioned to trail rotationally behind the first contoured cutting element while cutting to substitute for the first contoured cutting element if the first contoured cutting element becomes detached.
 2. The downhole cutting tool of claim 1, wherein the first contoured cutting element is attached to at least one of the body and the at least one contingency contoured cutting element.
 3. The downhole cutting tool of claim 2, wherein attachment of the first contoured cutting element to the at least one of the body and the at least one contingency contoured cutting element is by one of bonding, brazing, welding and gluing.
 4. The downhole cutting tool of claim 2, wherein material employed to attach the first contoured cutting element to the at least one of the body and the at least one contingency contoured cutting element is more ductile than at least one of the first contoured cutting element and the at least one contingency contoured cutting element.
 5. The downhole cutting tool of claim 2, wherein attachment of the first contoured cutting element to at least one of the body and the at least one contingency contoured cutting element is configured to fail prior to fracture of the first contoured cutting element.
 6. The downhole cutting tool of claim 2, wherein detachment of the first contoured cutting element from at least the body and the at least one contingency contoured cutting element stops a fracture in the first contoured cutting element from propagating into the at least one contingency contoured cutting element.
 7. The downhole cutting tool of claim 1, wherein the at least one contingency contoured cutting element is attached to the body.
 8. The downhole cutting tool of claim 1, wherein the first contoured cutting element and the at least one contingency contoured cutting element are oriented in at least one stack.
 9. The downhole cutting tool of claim 1, wherein a size of the first contoured cutting element limits a loss of volume of the downhole cutting tool associated with each detachment event.
 10. The downhole cutting tool of claim 1, wherein the first contoured cutting element includes a contoured cutting edge.
 11. The downhole cutting tool of claim 1, wherein the at least one of the first contoured cutting element and the at least one contingency cutting element are one of hard metal, ceramic and diamond.
 12. The downhole cutting tool of claim 11, wherein the hard metal is carbide.
 13. (canceled)
 14. A method of making a downhole cutter device comprising: substantially matching a contoured cutting edge of at least one contingency contoured cutting element with a contoured cutting edge of a first contoured cutting element; and attaching the at least one contingency contoured cutting element adjacent the first contoured cutting element positioned to trail rotationally behind the first contoured cutting element while cutting such that the at least one contingency contoured cutting element substitutes for the first contoured cutting element if the first contoured cutting element becomes detached.
 15. The method of making a downhole cutter device of claim 14, wherein the attaching is by one of bonding, brazing, welding and gluing.
 16. The method of making a downhole cutter device of claim 14, wherein the attaching is designed to fail at loads less than would cause fracture of the first contoured cutting element.
 17. A downhole cutter comprising: a plurality of cutting elements having substantially matched contoured cutting edges positioned perimetrically adjacent to one another; and a bonding material having greater ductility than the plurality of cutting elements bonding the plurality of cutting elements to one another in an arrangement such that detachment of one of the plurality of cutting elements reveals another of the substantially matched contoured cutting edges that substitutes for a contoured cutting edge of the detached cutting element.
 18. The downhole cutter of claim 17, wherein the downhole cutter is configured to allow detachment of one of the plurality of cutting elements under load prior to fracture of the one of the plurality of cutting elements.
 19. (canceled)
 20. The downhole cutting tool of claim 1, further comprising: a second contoured cutting element in operable communication with the body; and at least one contingency contoured cutting element in operable communication with the second contoured cutting element and the body, a contour of the at least one contingency contoured cutting element substantially matching a contour of the second contoured cutting element, the at least one contingency contoured cutting element being maintainable in reserve and positioned and displaced from the second contoured cutting element in a rotational direction of motion of the cutting elements while cutting to substitute for the second contoured cutting element if the second contoured cutting element becomes detached, and the detachability of the first contoured cutting element and the second contoured cutting element are independent from one another.
 21. The downhole cutting tool of claim 20, wherein independent detachment of the first contoured cutting element from the second contoured cutting element limits a volume of the downhole cutting tool that becomes detached during a detachment event. 